Loud-speaker



July 15, 1930. v E. REICHEL 1,770,494

LOUD SPEAKER Filed Dec. 15, 1924 INVENTOR 1 ATTORNEY Patented July 15, 1930 UNITED STATES PATENT OFFICE assronon 'ro GESELLSCHAFT run nm'r- GEBMANY, A- CORPORATION OF GERMANY LOUD-SPEAKER Application filed December-i5, 1924, Serial No. 755,887, and in Germany January 26, 1924.

, 151 in section, of a loudspeaker embodying t e principles of my invention.

- A disadvantage of all loud speakers known up till now is that. they have a distinct natural period and that consequently some notes were particularly amplified 'by resonance. The principle of the resent inven tion isto construct a loud spea er which has several natural periods, in order to attain such a resonance curve for the intensity of the sound that a larger range of frequencies is almost uniformly reproduced. Thispurpose H may be attained, for instance, by varying the shape of the horn and, at the same time, using a sounding board with variable adjustment for tuning purposes. I t

Consequently the loud s eaker represents a system of several perio ic devices which are coupled-to one another. By a pro er selection of the resonance frequencies 0 these single periodic devices, as well as by suitable coupling factors, very differently shaped resonance curves of the loud speaker may be obtained.

' According to the invention a loud speaker of the invention.

can, therefore, be constructed which is char-"- of the sounding board of the loud s eaker which may be of any of the well known types.

The sounding board 9 has an adjustable diaphragm'lO for adjusting the natural period of the board. a a Claims: i

1-. In combination, a loud speaker unit including'a born, a sound board physically connected with said horn, and means for varying the natural period of said sound 7 board.

2. In combination, a standard having a base, a loud-speaker unit supported by said standard, a horn supported by said standard to receive the sound waves from said unit,' a sound board connected to sa1d base to re:

ceive mechanical vibrations corresponding to the sound waves from said unit, and means for varying the natural period of said sound board.

3. In combination, a standard having a base, an opening through said-standard, a

loudspeaker unit positioned adjacent one side of sa1d opening, a horn for said unit positioned to receive the sound waves from the other side of said opening, said horn having a'predetermined natural period, and a sound board having an adjustable member for varyin the natural period of the sound board, sa1d sound board being connected to said base whereby 1 mechanical vibrations are transmitted from said horn and standard to s'aid'sound board.

4. A mechanical system for the amplification of sound vibrations having the combination of a' pluralit of resonant members, one of said members eing adjustable so as to have a different natural periodo-f vibration.

' 5. In a device for amplifying sound vibrations, the combination of a resonant base and a horn, said resonant base having independent adjusting means for varying its nat ural period of vibration.

6. In a device for translating electrical undulations into sound vibrations and for amplifyin the latter, a-hollow resonant base having a plunger therein for varying the natural period of the base, a member mounted on the base, a horn mounted on the member and a sound Wave producing unit associated with said horn. EUGEN BEICHEL. 

